Switched Driver Slew-Rate Shaping for Ringing Suppression
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Solution Overview
Problem
Switched power supplies experience ringing in the output voltage due to inherent inductance, which can lead to interference and decreased efficiency if the slew rate is not properly managed.
Innovation Solution
A switched driver circuit that includes a high-side and low-side switch, with a switch controller that dynamically adjusts the resistance of the switches to control the slew rate and attenuate ringing, by reducing and increasing the resistance in response to signal inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slew rate is increased to improve efficiency, then the efficiency of the power supply improves, but high frequency components propagate and interfere with operation
Solution Approach 1:
The patent applies dynamics by making the switch resistance time-dependent rather than static. The controller dynamically adjusts the resistance of the high-side or low-side switch during the switching transition, creating a time-varying resistance profile that first decreases then increases. This dynamic resistance modulation allows the system to achieve fast switching for efficiency while controlling the propagation of high frequency components through the shaped transition waveform.
Solution Approach 2:
The patent changes the resistance parameter of the switch during operation. By controlling the switch resistance to decrease initially and then increase during the switching event, the system modifies the electrical parameters to achieve both fast switching (for efficiency) and controlled slew rate (to limit high frequency interference). This parameter modulation resolves the contradiction between speed and interference.
2Object-generated harmful factors
If the slew rate is decreased to reduce high frequency interference, then interference is reduced, but the efficiency of the power supply decreases
Solution Approach 1:
The dynamic resistance adjustment during switching allows the system to have different effective slew rates at different times of the transition. The initial resistance decrease enables fast switching for efficiency, while the subsequent resistance increase limits the tail end of the transition to reduce high frequency interference. This time-dependent control resolves the contradiction between reducing interference and maintaining efficiency.
Solution Approach 2:
By modulating the switch resistance parameter during the switching event, the system achieves an optimized slew rate profile. The resistance changes create a non-linear transition that balances fast switching (for efficiency) with controlled high frequency content (to reduce interference), resolving the trade-off between these two opposing requirements.
3Speed
If the resistance of the switch is reduced to speed up switching, then the switching speed increases, but ringing occurs in the output voltage
Solution Approach 1:
The patent uses dynamic resistance adjustment to control the switching transition. By first decreasing then increasing the switch resistance during switching, the system achieves fast initial switching speed while the subsequent resistance increase dampens the ringing that would otherwise occur. This dynamic control allows the system to have fast switching without the stability degradation caused by ringing.
Solution Approach 2:
The resistance parameter is modulated during switching to achieve both fast switching and reduced ringing. The initial resistance decrease enables rapid switching, while the follow-up resistance increase acts to dampen oscillations and stabilize the output voltage, thus resolving the contradiction between switching speed and voltage stability.
4Stability of the object's composition
If the resistance of the switch is increased to reduce ringing, then ringing is reduced, but the switching speed decreases
Solution Approach 1:
The dynamic resistance profile that first decreases then increases during switching allows the system to have low resistance during the critical initial switching phase (for speed) and higher resistance during the settling phase (to reduce ringing). This time-dependent resistance control resolves the contradiction between switching speed and ringing reduction.
Solution Approach 2:
By changing the resistance parameter dynamically during the switching event, the system achieves fast switching initially (when low resistance is beneficial) and then transitions to higher resistance (to dampen ringing and stabilize output). This parameter modulation resolves the trade-off between speed and stability.
Data Source
AI summary
A switched driver for a power supply includes a high-side switch and a low-side switch coupled to the high-side switch. An output is coupled between the high-side switch and the low-side switch. A switch controller is coupled to either the high-side switch or the low-side switch and has a switch controller input for receiving a switch control signal and an output for controlling a switch. The switch controller initially reduces the resistance of the switch, increases the resistance of the switch, and then reduces the resistance of the switch in response to a signal received at the input.